The banana weevil Cosmopolites sordidus (Germar, 1824) (Coleoptera: Curculionidae) is an important pest of banana, plantain and ensete. The adult weevil is black and measures 10-15 mm. It is free living, though most commonly found between leaf sheaths, in the soil at the base of the mat or associated with crop residues. The weevil is nocturnally active and very susceptible to desiccation. Adults may remain at the same mat for extended periods of time, while only a small proportion will move > 25 m within 6 months. The weevils rarely fly. Dissemination is primarily through infested planting materials and thats why its important to use clean planting material.

Biology and life cycle The banana weevil Cosmopolites sordidus (Germar, 1824) (Coleoptera: Curculionidae) is an important pest of banana, plantain and ensete. The adult weevil is black and measures 10-15 mm. It is free living, though most commonly found between leaf sheaths, in the soil at the base of the mat or associated with crop residues. The weevil is nocturnally active and very susceptible to desiccation. Adults may remain at the same mat for extended periods of time, while only a small proportion will move > 25 m within 6 months. The weevils rarely fly. Dissemination is primarily through infested planting material. The banana weevil is a “k” selected insect with long life span and low fecundity. Many adults live 1 year, while some survive up to 4 years. On moist substrates, the weevil can survive without feeding for several months. The sex ratio is 1:1. Oviposition rates of more than 1 egg/day have been recorded, but, most commonly, oviposition has been estimated at 1 egg/week. The female places its white, oval eggs singly into holes made by the rostrum. Most oviposition is in the leaf sheaths and rhizome surface. Flowered plants and crop residues are favoured stages for oviposition. The emerging larvae preferentially feed in the rhizome, but will also attack the true stem and, occasionally, the pseudostem. The larvae pass through 5-8 instars. Pupation is in naked cells near the surface of the host plant. Developmental rates are temperature dependent. Under tropical conditions, the egg to adult period is 5-7 weeks. Egg development does not occur below 12°C; this threshold may explain why the weevil is rarely encountered above 1600 mas

Average duration of the larval period is 140 days for males and 151 days for females. Males and females have 8 and 9 development stages, respectively. At birth, larvae emerge from an opening on the lower end of the basket, they secrete a silk thread, and then spread assisted by the wind (foresia).

As they move down any plant, they begin to scrape the epidermis of the leaves, using the remnants, stuck together with saliva, to form the basket. As the larva develops, it enlarges the basket with pieces of leaves, twigs and veins.

Where populations of economic relevance are observed, or when a general infestation is detected, spray with Bacillus thuringiensis in doses from 350 to 400 g/hectare.

The product must be used immediately after mixing, and the application must be done in the early morning. It is advisable to use motorized equipment to apply the product with a bonding agent at 2.5% volume over the whole surface.

Eggs are laid on the reverse side of the leaves and 28 days Figure 2. Ceramidia larva 5-6 days.

As the larva grows, the band size increases. Damage is perpendicular to the central vein, finally perforating the leaf. The chrysalis is surrounded by numerous larva hairs, which protect against environmental conditions and predators. Chrysalises are found mostly along the central vein on the underside of the leaf, on the shoot and occasionally on the bunch.

This pest damages banana and plantain crops. Adults are butterflies and moths with sizes ranging from 8 to 10 cm. The forewings are dark brown, with a white or yellow band near the wingtip, and two small white spots. Hind wings are dark brown with reddish tones.

Male Opsiphanes show two hairy tufts, not so females. Spots on the ventral section resemble eyes. Adults spend the day on rejected fruit or rotting bunches feeding on their sugary substances

Larvae look for dry places to form chrysalis, which are kidney-shaped and yellowish-green when recently formed, and turn light brown shortly before the butterfly emerges. They also show a small silver area on the sides, near the end of the body.

Damage

When 5 to 8 larvae appear in the middle third of the leaves, or when more, then 20% of the leaf surface has been eaten.

Limited supply of high-yielding and disease-free banana planting materials of three banana cultivars hinders growers to use tissue-cultured materials and to operate diversified farms.

There were banana growers who chose to utilize planting materials from their farms or those from their neighborsor relatives, some of which are infected by pests and diseases, instead of shouldering the higher cost of tissue-culture planting materials. Also, despite better yields realized in diversified banana cultivar farming.

High incidence of pests and diseases reduces banana yield in Oriental Mindoro. Through the adoption of site-specific Integrated Pest Management (IPM) and dissemination of information on banana pests and diseases and their control, the effects of these infestations would be minimized.chances of pathogen entering the rhizomes, roots and stem of banana plant.

The vast majority of the bananas currently grown and consumed were not conventionally bred but are selections made over probably thousands of years from naturally occurring hybrids. Cultivated bananas are very nearly sterile and as a consequence are not propagated from seed but rather through vegetative propagation, primarily suckers as well as more recently micropropagated or tissue cultured bananas. These factors, very old selections, near sterility and vegetative propagation, mean that these bananas have not been genetically improved either for resistance or improved quality and are becoming increasing in affected by serious pests and diseases.